Suffolk’s Democrats gathered on May 20, but rather than select an Assembly candidate the party took the unusual step of putting the choice in the hands of the party committees within the 2nd Assembly District, which extends from north central Brookhaven east to Fishers Island.

Riverhead’s Democrats met first, holding their convention last Thursday night, and offering their support for Mr. McManmon. The voting was weighted based on the number of gubernatorial votes cast in each town in the last state elections.

The Riverhead committee gave 4,280 votes to Mr. McManmon. He picked up another 1,843.5 at the Brookhaven contention Tuesday night to give him a total of 6,123.5. Ms. Maertz received 2,196.5. Even if Southold gave all of its votes to Ms. Maertz, which appeared unlikely, she would still come in second to Mr. McManmon. None of the other candidates came close.

Although its votes won’t affect the outcome, Southold was expected to support Jim Waters, the owner of Waters Crest Winery and a Manorville resident.

“I think he’s extremely well qualified and we’re going to do all we can to support him,” said Art Tillman, Southold Democratic Committee leader.

Although it appears he’s receive the nomination, there’s been a backlash over Mr. McManmon’s candidacy based on his residency. Mr. McManmon, 28, works for a Manhattan law firm called Millbank, Tweed, Hadley and McCoy, and his address is listed as that of his parents in Aquebogue, although some have said he lives at an apartment on Dean Street in Brooklyn.

He said last Thursday that although he lives in Brooklyn during the week for work purposes, he still votes here.

Mr. McManmon’s father, James, is an attorney who works for OTB and who has made three unsuccessful runs at a state Assembly seat. His mother, Jeanne O’Rourke, is a deputy commissioner for the Board of Elections.

“If you check with the Board of Elections, John has been registered from his family address since he was 18,” said Riverhead Democratic Committee chairwoman Marge Acevedo. “His job is in New York City and he travels back and forth. His residency should not be in question at all. There are no real jobs out here and people should take that into consideration. Once everybody meets him they’ll know he was born and bred in Riverhead.”

Referring to the name of Riverhead School District athletic teams, she added, “He’s a Blue Waves kid.”